Submission #2499736

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Source Code Expand

#include"bits/stdc++.h"
using namespace std;

int main() {
    string s;
    int K;
    cin >> s >> K;

    vector<int> num(26, 0);
    for (char c : s) {
        num[c - 'a']++;
    }

    set<string> st;
    for (int i = 0; i < 26; i++) {
        for (int j = s.size() - 1; j >= 0; j--) {
            if (s[j] == i + 'a') {
                for (int k = 1; k <= K; k++) {
                    st.insert(s.substr(j, k));
                }
            }
        }

        if (st.size() >= K) {
            int counter = 0;
            for (auto itr = st.begin(); itr != st.end(); itr++) {
                if (++counter == K) {
                    cout << *itr << endl;
                    return 0;
                }
            }
        }
    }
}

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